Using “Mulla’s Formula” to Estimate Percent Control

Reisen, William K.

doi:10.1007/978-90-481-2458-9_9

Cited by 7 publications

(16 citation statements)

References 15 publications

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“…As a comparison for our model results, we applied the conventional approach of Mulla’s formula [ 16 , 17 ] to the combined trapping and control records from 2006 to 2017 to estimate the efficacy of sprays. Considering trapping 1 week before and 1 week after a spray event and using a 5-km buffer around the targeted spray zone as the adjacent comparison area, we were able to calculate the effect for 36 spray events (3.87%) for Cx.…”

Section: Resultsmentioning

confidence: 99%

“…For each draw, we then calculated the mean change in abundance from the baseline no-spray scenario at each point on the spatio-temporal surface, along with the corresponding 95% confidence interval (CI). Estimates of efficacy from the model were compared with those derived from Mulla’s formula [ 16 , 17 ].…”

Section: Methodsmentioning

confidence: 99%

“…A standard method for evaluating the efficacy of an aerial spray event compares pre- to post-treatment mosquito trap counts inside the treatment zone versus changes for the same period in an adjacent unsprayed control area [ 16 ]. This method, first proposed by Mulla et al [ 17 ], has been adapted to and widely used in evaluating the efficacy of aerial spraying for reducing the abundance of female mosquitoes and has been extended to assess changes in other indicators of risk, namely infection prevalence in mosquitoes, human cases and reported dead birds, with WNV infection [ 16 ]. However, reported estimates vary widely, with some studies even indicating occasional increases in trap counts following spray events [ 18 – 21 ].…”

Section: Introductionmentioning

confidence: 99%

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Spatio-temporal impacts of aerial adulticide applications on populations of West Nile virus vector mosquitoes

2021

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Background Aerial applications of insecticides that target adult mosquitoes are widely used to reduce transmission of West Nile virus to humans during periods of epidemic risk. However, estimates of the reduction in abundance following these treatments typically focus on single events, rely on pre-defined, untreated control sites and can vary widely due to stochastic variation in population dynamics and trapping success unrelated to the treatment. Methods To overcome these limitations, we developed generalized additive models fitted to mosquito surveillance data collected from CO2-baited traps in Sacramento and Yolo counties, California from 2006 to 2017. The models accounted for the expected spatial and temporal trends in the abundance of adult female Culex (Cx.) tarsalis and Cx. pipiens in the absence of aerial spraying. Estimates for the magnitude of deviation from baseline abundance following aerial spray events were obtained from the models. Results At 1-week post-treatment with full spatial coverage of the trapping area by pyrethroid or pyrethrin products, Cx. pipiens abundance was reduced by a mean of 52.4% (95% confidence intrval [CI] − 65.6, − 36.5%) while the use of at least one organophosphate pesticide resulted in a mean reduction of 76.2% (95% CI − 82.8, − 67.9%). For Cx. tarsalis, at 1-week post-treatment with full coverage there was a reduction in abundance of 30.7% (95% CI − 54.5, 2.5%). Pesticide class was not a significant factor contributing to the reduction. In comparison, repetition of spraying over three to four consecutive weeks resulted in similar estimates for Cx. pipiens and estimates of somewhat smaller magnitude for Cx. tarsalis. Conclusions Aerial adulticides are effective for achieving a rapid short-term reduction of the abundance of the primary West Nile virus vectors, Cx. tarsalis and Cx. pipiens. A larger magnitude of reduction was estimated in Cx. pipiens, possibly due to the species’ focal distribution. Effects of aerial sprays on Cx. tarsalis populations are likely modulated by the species’ large dispersal ability, population sizes and vast productive larval habitat present in the study area. Our modeling approach provides a new way to estimate effects of public health pesticides on vector populations using routinely collected observational data and accounting for spatio-temporal trends and contextual factors like weather and habitat. This approach does not require pre-selected control sites and expands upon past studies that have focused on the effects of individual aerial treatment events.

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Section: Resultsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Spatio-temporal impacts of aerial adulticide applications on populations of West Nile virus vector mosquitoes

2021

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“…For each draw, we then calculated the mean change in abundance from the baseline no-spray scenario at each point on the spatio-temporal surface, along with the corresponding 95% con dence interval. Estimates of e cacy from the model were compared with those derived from Mulla's formula (16,17).…”

Section: Discussionmentioning

confidence: 99%

“…As a comparison for our model results, we applied the conventional approach of Mulla's formula (16,17) to the combined trapping and control records from 2006-2017 to estimate the e cacy of sprays. Considering trapping one-week before and after a spray event and using a 5km buffer around the targeted spray zone as the adjacent comparison area, we were able to calculate the effect for 30 spray events (3.23%) for Cx.…”

Section: Comparison To Conventional Estimatesmentioning

confidence: 99%

Spatio-Temporal Impacts of Aerial Adulticide Applications on Populations of West Nile Virus Vector Mosquitoes

Holcomb

Reiner

Barker

2020

Preprint

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Background: Aerial applications of insecticides that target adult mosquitoes are widely used to reduce transmission of West Nile virus to humans during periods of epidemic risk. However, estimates of the reduction in abundance following these treatments typically focus on single events and can vary widely due to stochastic variation in population dynamics and trapping success unrelated to the treatment.Methods: To overcome these limitations and assess real-world efficacy using observational data from 12 years of vector control operations, we fitted generalized additive models to mosquito surveillance data from CO2-baited traps in Sacramento and Yolo counties, California from 2006-2017. The models accounted for the expected spatial and temporal trends in the abundance of adult female Culex tarsalis and Culex pipiens in the absence of aerial spraying. Estimates for the magnitude of deviation from baseline abundance following aerial spray events were obtained from the models.Results: One-week post-treatment with pyrethroid or pyrethrin products, Cx. pipiens abundance was reduced by a mean of 52.4% (95% CI: -65.6, -36.5%) while the use of at least one organophosphate pesticide resulted in a 76.2% (95% CI: -82.8, -67.9%) reduction. For Cx. tarsalis one-week post-treatment resulted in a 30.7% (95% CI: -54.5, 2.5%) reduction; pesticide class was not a significant factor for this species. Repetition of spraying over three to four consecutive weeks resulted in similar estimates for Cx. pipiens and a somewhat smaller magnitude for Cx. tarsalis.Conclusions: Aerial adulticides are effective for rapid short-term reduction of the abundance of the primary West Nile virus vectors, Cx. tarsalis and Cx. pipiens. A larger magnitude of reduction is estimated for Cx. pipiens, possibly due to the species’ focal distribution. Effects of aerial sprays on Cx. tarsalis populations are likely moderated by the species’ large dispersal ability, population sizes, and vast productive larval habitat present in the study area. Our modeling approach provides a way to estimate effects of public-health pesticides on vector populations using real-world observational data and accounting for contextual factors like spatio-temporal relationships, weather, and habitat and expands upon past studies that have focused on effects of individual aerial treatment events.

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Evaluation of a promising new botanical adult mosquito repellent on horses

Talbalaghi¹,

Ammar²,

Hassandoust³

2018

J Transl Sci

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Repel Care®, a botanical adult mosquito repellent, containing primarily turmeric and eucalyptus oils, was topically applied at 3.4 and 6.9 grams/m 2 surface area on sports horses and evaluated to repel adult mosquitoes (predominantly Ochlerotatus caspius) in a horse stable situated amid a rice field area in Alessandria, south Piedmont, Italy. The repellent gave satisfactory results with an overall mean repellence of 62.3% of adult mosquitoes (range 29.1 to 88.4%) during the four evenings of evaluation. Higher rates of application of the repellent may yield better results in terms of magnitude and persistence.

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Using “Mulla’s Formula” to Estimate Percent Control

Cited by 7 publications

References 15 publications

Spatio-temporal impacts of aerial adulticide applications on populations of West Nile virus vector mosquitoes

Spatio-temporal impacts of aerial adulticide applications on populations of West Nile virus vector mosquitoes

Spatio-Temporal Impacts of Aerial Adulticide Applications on Populations of West Nile Virus Vector Mosquitoes

Evaluation of a promising new botanical adult mosquito repellent on horses

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